dojo.store.Observable global not set when using AMD require()

In [28515] I accidentally set the global dojo.store.util.Observable rather than dojo.store.Observable.

Luckily, dojo.require("dojo.store.Observable") still creates a global variable called dojo.store.Observable, thanks to code in dojo.require(). However, it isn't created when using AMD's require() method, even though it was created in 1.7.